Refrigerator

ABSTRACT

A refrigerator comprising a housing, a pair of doors, link devices, and damping devices. Each of the damping devices includes a casing defining the appearance of the damping device, a cam member, a piston, a sealing member fitted around the piston, a spring, a guide rod, and a cap member connected to the guide rod so as to be positioned inside the casing. Since the damping device of the present invention is reducible in size, and is vertically mountable by virtue of its reduced operating space, it can be installed inside a refrigerator door or refrigerator housing, rather than the bottom surface of the refrigerator. Especially, the damping device can be mounted inside the lower end portion of a front panel of the refrigerator door, resulting in ease in exchange and repair thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 2004-36260, filed on May 21, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a refrigerator, and, more particularly, to a damping device of a refrigerator which reduces an operating space thereof, and a simplified link device to realize the damping device.

2. Description of the Related Art

Generally, in order to protect a refrigerator as well as various foods stored therein, the refrigerator is provided with damping devices, which serve to absorb shock generated upon a closing of refrigerator doors so as to secure a smooth closing operation of the doors. As such, a damping device has conventionally been a device using oil. This kind of damping device, however, has a problem in that a sealing member thereof is often worn due to rectilinear reciprocation of a rod provided in a link device of the damper. Here, the link device is horizontally mounted at the bottom of a refrigerator. To achieve the rectilinear reciprocation of the rod, the link device must have disadvantageously long links.

Another problem of the conventional damping device is that the damping device requires a separate structure to be used in the protection of an oil damper as well as the links of the link device.

In such a conventional damping structure of refrigerator doors as stated above, further, since the links of the link device tend to bend due to an external force applied to the refrigerator door, there exists the need for a wide operating space to avoid interference of the links.

In most cases, furthermore, since the conventional damping device is provided at the bottom of a refrigerator housing so that the conventional damping device connects the refrigerator housing to a refrigerator door by cooperating with the link device, to repair of the damping device, the refrigerator housing has to be laid down on the ground after all foods therein are taken out, resulting in extreme trouble in repair and exchange thereof.

SUMMARY OF THE INVENTION

Therefore, an aspect of the present invention provides a refrigerator comprising a damping device of a refrigerator door, which is mountable even in a narrow space by virtue of a reduced operating space of the damping device, and a simplified link device, which enables the damping device to be mounted to the refrigerator door without interference of other members.

Another aspect of the invention is to provide a refrigerator comprising a damping device, which is designed to be mounted in a separate space defined in a refrigerator door, resulting in simplicity in repair and exchange thereof.

Accordingly, the present invention provides a refrigerator comprising a housing, and a pair of doors coupled to the housing in a hingedly rotatable manner, and further comprising: link devices to be used in the transmission of a rotating force of the doors relative to the housing; damping devices, each of which is coupled to one end of the respective link devices, to absorb shock applied to the doors, and/or to allow the doors to be automatically closed.

Each of the damping devices may include: a casing to define the appearance of the damping device; a cam member to convert a rotating motion of an associated one of the doors into a linear motion thereof: a piston coupled to the cam member inside the casing so as to linearly move; and oil charged inside the casing to exert damping operation through a volume constriction or expansion thereof, which is caused by the linear motion of the piston.

The damping device may be mounted in a separate mounting space that is vertically defined inside the door.

The cam member of the damping device may take the form of a hollow shaft having spiral grooves, and the piston may be coupled to the cam member so as to linearly move along the spiral grooves. As a result, the cam member may serve to convert the rotating motion of the door, transmitted through an associated one of the link devices, to the linear motion of the piston.

The cam member may be positioned inside the cylindrical casing so that a link connecting portion that is provided at one end thereof protrudes outwardly to allow the link device to be rotatably fitted therearound.

The damping device may further include a sealing member, which is fixed around the piston to seal the oil charged around the piston inserted inside the casing.

The cam member and the piston may be coupled to each other by means of guide pins so that the piston is linearly movable within a range of the spiral grooves formed at the cam member.

The guide pins may be located close to a lower end of the cam member in a closed state of the door, and slide upward along the spiral grooves toward an upper end of the cam member by receiving an external force when the door is opened, so as to allow the oil to be compressed by a sealing member. As a result, the guide pins may serve to allow the door to be smoothly closed or be automatically closed as they are returned toward the lower end of the cam member by making use of a repulsive force of the oil.

Further, the present invention also provides a refrigerator comprising a housing, and a pair of doors coupled to the housing in a hingedly rotatable manner, and further comprising: damping devices provided at the doors or the housing; and link devices to connect the housing and the respective doors in order to transmit a rotating force of the doors to the damping devices.

Each of the link devices may include a first link member and a second link member.

Each of the first and second link members may have rotatably connectable joint portions at both ends thereof.

The first and second link members may partially overlap each other while forming a small angle therebetween in a closed state of an associated one of the doors, whereas they may be spaced apart from each other by a certain large angle when the door is opened.

Fasteners to rotatably connect the first and second link members to each other may be coupled to respective joint portions.

The link device may be positioned adjacent to a center axis of rotation of an associated one of the doors relative to the housing.

The link device may include a hinge member and a hinge shaft, and one end of the hinge member is fixed to the housing, and the other end of the hinge member is coupled to associated one of the doors by means of the hinge shaft so as to secure rotation of the door.

Additional and/or other aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a perspective view illustrating the mounting position of a damping device of a refrigerator in accordance with the present invention;

FIG. 2 is an exploded perspective view illustrating a link device, to which the damping device of a refrigerator in accordance with the present invention is coupled;

FIG. 3 is a perspective view illustrating an assembled state of the link device in accordance with the present invention;

FIG. 4 is an exploded perspective view illustrating the structure of the damping device in accordance with the present invention;

FIG. 5 is a front view illustrating the structure of the link device in accordance with the present invention, in a state in which a refrigerator door is closed;

FIG. 6 is a front view illustrating the structure of the link device in accordance with the present invention, in a state in which the refrigerator door is opened;

FIG. 7 is a sectional view illustrating the operation of the damping device in accordance with the present invention, in a state in which the refrigerator door is closed; and

FIG. 8 is a sectional view illustrating the operation of the damping device in accordance with the present invention, in a state in which the refrigerator door is opened.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.

A preferred embodiment of the present invention will now be described in detail with reference to the annexed drawings. FIG. 1 is a perspective view illustrating the mounting position of a damping device for a refrigerator in accordance with the present invention.

The refrigerator, according to the present invention, comprises a rectangular housing 1 that is open at a front side thereof, and doors 3 and 4 which are coupled to the housing 1 in a hingedly rotatable manner. The doors 3 and 4 open or close the open front side of the housing 1. The doors 3 and 4 are coupled to the housing 1 via link devices 10 provided at an upper or lower end thereof. Damping devices 20, to which the link devices 10 are connected, are provided at an upper or lower end of the housing 1. The damping devices 20 secure smooth opening and closing operations of the doors 3 and 4. Consequently, the damping devices 20 prevent shock from being applied to the housing 1. In a “side by side type refrigerators,” two damping devices 20 are provided inside the doors 3 and 4 in a one to one ratio.

The interior of the refrigerator is divided into a left freezing chamber, and a right refrigerating chamber, which are both designated by reference numeral 2. A plurality of shelves 5 and storage containers 6 to store foods are provided inside the freezing and refrigerating chambers 2. Shelves 7 to store beverages or small containers are provided at the inner surfaces of the doors 3 and 4.

FIG. 2 is an exploded perspective view illustrating the link device 10, to which the damping device 20, in accordance with the present invention, is coupled. In the present embodiment, the damping devices 20 are provided inside the doors 3 and 4 in a one to one ratio, and each of the damping devices 20 is mounted in a separate mounting space defined in the respective doors 3 and 4 so as to achieve convenience in repair and exchange thereof. Such a separate mounting space is defined in the lower portion of a front panel of the respective doors 3 and 4, but a position thereof is not limited thereto,. As such, the position of the mounting space may be defined in other portions of the doors 3 and 4, or in the housing 1 since the damping device 20 of the present invention has substantially fewer of the spatial problems encountered when using a conventional link device, which requires a wide horizontal space.

Such a damping device 20 includes a link connecting portion 21 formed at one end thereof. The link connecting portion 21 is inserted through a cylindrical guide portion 11 a that is provided at a rectangular plate-shaped support member 11 so as to protrude out of the support member 11. The support member 11 is further provided with a center opening 11 b to be used in the insertion of the link connection portion 21, and a plurality of bolt fastening holes 11 c to be used in the fastening of the support member 11 to the door 3 or 4.

A first link member 12 is coupled to the link connecting portion 21, which was inserted through the support member 11 so as to protrude out of the support member 11. The first link member 12 has a bar shape, and is formed at one end thereof with a first hole to be used in the coupling of the link connecting portion 21, and at the other end thereof with a second hole to be used in the coupling of a second link member 15.

The second link member 15 has a bar shape that is similar to the first link member 12. However, the second link member 15 is longer than the first link member 12. By using fasteners 13, 14 and 16, such as bolts, pins, nuts, etc., one end of the second link member 15 may be coupled to the first link member 12, and the other end of the second link member 15 is coupled to a hinge member 17. In consideration of such a bar shape, the first and second link members 12 and 15 are made of a metallic material having strength and durability that is sufficient to endure the load of the refrigerator door.

The hinge member 17 has a plate shape, but a shape thereof is not limited thereto. As such, the hinge member 17 may have other appropriate shapes in consideration of the coupling relationship between the door 3 or 4 and the housing 1. In the present embodiment, the hinge member 17 is fixed at one end thereof to the refrigerator housing 1, and is fixed at the other end thereof to the refrigerator door 3 or 4 by means of a hinge shaft 18. The hinge member 17 has an area that is sufficient to support the load of the refrigerator door.

The hinge member 17 is formed with a threaded protrusion 17 a to be used in the coupling of the second link member 15, and an opening 17 b to be used in the coupling of a hinge shaft coupling member 19. The hinge shaft coupling member 19 is fastened to the end of the bottom surface of the door 3 or 4. The hinge member 17 further includes a plurality of threaded holes 17 c to allow the hinge member 17 to be firmly fastened to both of the refrigerator doors 3 or 4 and the housing 1 in order to connect the hinge member 17 with the refrigerator doors 3 or 4 and the housing 1.

FIG. 3 is a perspective view illustrating an assembled state of the link device 10 in accordance with the present invention.

The link device 10, having the link members, is coupled to the damping device 20, as shown in FIG. 3. The damping device 20 is mounted inside the door 4. The support member 11 is bolted to the lower end of the door 4 so that the link connecting portion 21 of the damping device 20 protrudes out of the support member 11 through the center opening 11 b. The first hole of the first link member 12 is fitted to the link connecting portion 21. A nut is then fixedly fastened therearound.

The second link member 15 is bolted to the first link member 12. The two link members 12 and 15 move according to opening and closing operations of the refrigerator door. Therefore, in order to relieve friction between the first and second link member 12 and 15 that occurs during rotation of the doors 3 or 4, a washer is interposed between the first and second link members 112 and 15. The second link member 15 is fixedly coupled to the hinge member 17 having a large area as one of the holes thereof is fitted around the protrusion 17 a of the hinge member 17, and a nut is fastened therearound.

The hinge shaft 18 is fitted through the opening 17 b of the hinge member 17. The hinge shaft 18 is further fitted in a hinge shaft opening 19a of the hinge shaft coupling member 19, which would have been previously fastened to the end of the bottom surface of the refrigerator door so as to fix the hinge member 17 to the door. The threaded holes 17 c of the hinge member 17 are respectively aligned with and bolted to holes formed at the refrigerator housing 1 so as to allow the hinge member 17 to be firmly fastened to the refrigerator housing 1. The hinge shaft coupling member 19, having the hinge shaft opening 19 a, which is provided at the end of the bottom surface of the refrigerator door, simplifies the coupling of the hinge member 17 to the refrigerator door.

FIG. 4 is an exploded perspective view illustrating the structure of the damping device 20 in accordance with the present invention.

Referring to FIG. 4, the damping device 20 comprises a cam member 22 to be coupled to the support member 11. A casing 29 is threaded into the cylindrical guide portion 11 a of the support member 11. The link connecting portion 21 of the cam member 22, having an elliptical shape, is inserted through the center opening 11 b of the support member 11. As a result, the motion of the link members, which are coupled to the support member 11, is transmitted to the cam member 22 to induce the operation of the damping device 20 in correspondence to the opening and closing operations of the refrigerator door.

The cam member 22 is coupled to the support member 11 through the link connecting portion 21 provided at one end thereof. The diameter of the cam member 22 is larger than that of the link connecting portion 21. Spiral grooves 22 a and 22 b are formed at the outer periphery of the cam member 22. Both ends of the respective spiral grooves 22 a and 22 b are rounded, and have a diameter larger than that of the remaining portion of the respective spiral grooves 22 a and 22 b.

Rotatably fitted guide pins 23 extend through the one-side ends of the spiral grooves 22 a and 22 b. The guide pins 23 serve to momentarily keep the refrigerator door in a completely opened position so as to secure a smooth damping operation, as well as to stably keep a closed state of the door. The diameter of the guide pins 23 is substantially the same as that of the remaining portion of the respective spiral grooves 22 a and 22 b to allow the guide pins 23 to slide along the spiral grooves 22 a and 22 b, respectively, without separation.

Each of the guide pins 23 has a threaded portion 23 a at one end thereof to secure an easy assembly thereof, as well as a pin head at the other end thereof. Where a piston 24 is inserted in the cam member 22, the threaded portions 23 a of the guide pins 23 are fitted in two coupling holes 24 a that are formed at the lower end region of a piston 24 by passing the threaded portions 23 a of the guide pins through the spiral grooves 22 a and 22 b of the cam member 22.

A sealing member 25 is provided around the circumference of the piston 24. The sealing member 25 seals oil that is charged around the piston 24 between the sealing member 25 and a cap member 28. The cap member 28 is located at the distal end of a guide rod 27. The sealing member 25 is formed with a small through-hole 25 a to allow the oil to be supplied to the cam member 22 so as to achieve a smooth operation of the cam member 22. The sealing member 25 also supports a spring 26, which is fitted around the piston 24. To this end, the sealing member 25 is fixedly coupled around the piston 24 so as not to move along the piston 24.

The piston 24 is hollow, and the guide rod 27 may be inserted therein in a vertically movable manner. The insertion of the guide rod 27 into the piston 24 is possible because the guide rod 27 has a diameter that is smaller than an inner diameter of the piston 24. The cap member 28, provided at the distal end of the guide rod 27, has a disk shape, and contacts with an upper end of the piston 24 according to the motion of the guide rod 27.

The cross-sectional shapes of the guide rod 27 and the cap member 28 are not perfectly circular, and may instead be partially cut-away circles. Such a shape is effective to allow the guide rod 27 to linearly move inside the piston 24 without rotation when the cam member 22 is rotated upon an opening of the refrigerator door. Of course, the cross sectional shapes of the guide rod 27 and the piston 24 are not limited to partially cut-away circles and may be freely selected from among a square and other shapes so long as the shaped of the guide rod 27 and the piston 24 may prevent rotation of the guide rod 27.

That is, the guide rod 27 and the piston 24 are designed to only linearly move inside the casing 29. Meanwhile, the cam member 22 is designed to rotate around the piston 24.

The spring 26, interposed between the guide rod 27 and the piston 24, has a length that is equal to the sum of the length of the guide rod 27 and the length from the upper end of the piston 24 to the sealing member 25 that is fixed around the piston 24. As the cap member 28 vertically moves according to linear motion of the guide rod 27 coupled thereto, the spring 26 contracts or extends.

The interior of the casing 29 is charged with the oil in he region of the casing 29 that extends from the sealing member 25 to the cap member 28 when the cap member 28 is coupled to the guide rod 27. Part of the oil is supplied into the cam member 22 along the spiral grooves 22 a and 22 b by passing through the through-hole 25 a formed at the sealing member 25, resulting in smooth driving of the cam member 22. One end of the casing 29 is blocked, and the other end thereof is formed with a threaded portion 29 a to allow the casing 29 to be threaded to the cylindrical guide portion 11 a of the support member 11.

FIG. 5 is a front view to illustrate the structure of the link device 10 in accordance with the present invention, in a state in which the refrigerator door 4 is closed. In such a state, the first link member 12 and the second link member 15 of the link device 10 are angled with respect to each other rather than completely overlapped. Such an arrangement is effective to support the load of the refrigerator door in rotation as well as a stationary state.

FIG. 6 is a front view to illustrate the structure of the link device 10 in accordance with the present invention, in a state in which the refrigerator door 4 is opened to the right by an angle of 90 degrees compared to FIG. 5. In general, the refrigerator door is openable through an angle of approximately 135 degrees.

As the refrigerator door 4 is opened, the support member 11 that is fixed to the door 4 is displaced to the right and rotated along with the door 4, and accordingly, a joint portion between the first link member 12 coupled to the support member 11 and the second link member 15 is displaced to the right. Thereby, the second link member 15 is hingedly rotated in a rotating direction of the door 4.

Upon opening the door 4, the link connecting portion 21, which was rotatably mounted to the door 4, is rotated. Such a rotation of the link connecting portion 21 is converted into linear motion of the piston 24 by the cam member 22.

FIG. 7 is a sectional view to illustrate the operation of the damping device 20 in accordance with the present invention, in a state in which the refrigerator door is closed. The configuration of the damping device 20 is previously explained in the above description in relation with FIG. 4. In a closed state of the door, the guide pins 23 are located at the lower ends of the spiral grooves 22 a and 22 b of the cam member 22.

The support member 11 is coupled at the lower end of the damping member 20 so that the link connecting portion 21 is inserted through the support member 11 so as to protrude out of the support member 11. In this case, the casing 29 of the damping device 20 is seated in the cylindrical guide portion 11 a having a certain height.

The cam member 22, the piston 24, and the guide rod 27 are successively inserted inside the casing 29, seated in the support member 11. The spring 26 is interposed between the guide rod 27 and the piston 24. The cam member 22 has a hollow structure so that the piston 24 may be inserted therein. The piston 24 is linearly movable inside the cam member 22 as the guide pins 23 slide along the spiral grooves 22 a and 22 b of the cam member 22.

The sealing member 25 is coupled around the piston 24 at a height that is sufficient to allow the sealing member 25 to be spaced apart from the upper end of the cam member 22 by a certain distance in the lowermost position of the piston 24. As stated above, the sealing member 25 is fixed to the piston 24 to support the spring 26 upon an extension or a contraction of the spring 26. In this way, the sealing member 25 serves not only as an oil sealing member, but also as a spring support member.

In a closed state of the refrigerator door, the guide pins 23 are positioned at the lower ends of the spiral grooves 22 a and 22 b of the cam member 22. Thus, the piston 24, being connected to the guide pins 23, is in the lowermost position inside the hollow cam member 22. In this case, since no pressure is applied to the guide rod 27, the cap member 28 connected to the guide rod 27 is positioned at an upper end of the casing 29 by the elasticity of the spring 26. That is, the spring 26 is in a completely extended state.

FIG. 8 is a sectional view to illustrate the operation of the damping device 20 in accordance with the present invention, in a state in which the refrigerator door is opened. Where the refrigerator door is opened by receiving an external force, the link connecting portion 21, which was connected to the refrigerator door so as to protrude out of the support member 11, is rotated by the link members (not shown) connected to the refrigerator door to force the guide pins 23 to slide upward along the spiral grooves 22 a and 22 b of the cam member 22. Such an upward movement degree of the guide pins 23 depends on the opening degree of the refrigerator door. In a completely opened state of the refrigerator door, the guide pins 23 are positioned at the upper ends of the spiral grooves 22 a and 22 b.

As a result, the piston 24, which was coupled to the guide pins 23 so as to vertically move inside the cam member 22, compresses the oil and the spring 26 by making use of the sealing member 25 sealably coupled around the piston 24. Since the oil and the spring 26 have a tendency to restore their original states by their shock absorbing and elastic properties, the door may be smoothly closed, and may automatically close when the door is opened within a range that is not more than a predetermined angle.

When the refrigerator door is closed, a force, applied to the guide pins 23, is released. Thus, the guide pins 23 slide downward along the spiral grooves 22 a and 22 b due to gravity and the elasticity of the spring 26. As a result, the guide pins 23 become seated in the lower ends of the spiral grooves 22 a and 22 b as shown in FIG. 7. In this case, even if the refrigerator door is closed with an extremely strong external force, the resulting shock may be absorbed by the elastic spring 26 and the oil charged in the casing 29. As a further result, since the guide pins 23 slowly slide downward along the spiral grooves 22 a and 22 b by a restoration force of the spring 26 and a repulsive force of the oil against the volume constriction thereof, the link connecting portion 21 connected thereto is accordingly slowly rotated, the refrigerator door is smoothly closed.

Now, the operation and effects of the preferred embodiment of the present invention will be explained in detail. The present invention includes a feature in that the damping device 20 and the link device 10 connected thereto are mounted at the lower end of the front panel of the door.

Different from the conventional damping device and by virtue of a reduced operating space, the damping device 20 may be mounted vertically inside the refrigerator door or the refrigerator housing within a narrow space, without requiring to be horizontally installed along the lower end of the housing 1. In this way, the overall structure of the link device 10 is simplified. Further, the device may be sufficiently operable by only two link members.

Now, the rotation of the damping device 20 using the hinge member 17 will be explained in detail.

In a closed state of the refrigerator door, the damping device 20 is in a state as shown in FIG. 7, and the link device 10 connected thereto is in a state as shown in FIG. 5. If an external force causes the door to be opened, the first link member 12 and the second link member 15 are hingedly rotated so that they are spaced apart from each other. Thus the link connecting portion 21 of the cam member 22 mounted in the door is rotated to cause the guide pins 23, fitted in the lower end of the piston 24, to slide upward along the spiral grooves 22 a and 22 b of the cam member 22. As a result, the piston 24 is moved upward so that the sealing member 25 fixed therearound compresses the spring 26 and the oil, while allowing the guide rod 27 to be inserted therein. Since a rotating angle of the link connecting portion 21 is variable according to an opening angle of the door, the position of the guide pins 23 as well as the compression of the spring 26 and the oil are correspondingly variable.

When the door begins to close again, the guide pins 23 are positioned at the upper ends of the spiral grooves 22 a and 22 b. As the closing operation of the door progresses, the first and second link members 12 and 15 are moved toward each other, and the link connecting portion 21 is rotated in an opposite direction of the opening direction of the door. At the moment when the link connecting portion 21 begins to rotate, the guide pins 23 are momentarily immobilized, and then slide downward to the lower ends of the spiral grooves 22 a and 22 b due to their gravity, the restoration force of the spring 26, and the repulsive force of the oil.

Even if a relatively strong external force closes the door, the spring 26 and the oil are slowly returned to their original states, resulting in damping effect.

As is apparent from the above description, since the damping device of a refrigerator in accordance with the present invention is reduced in size, and is vertically mountable by virtue of the reduced operating space thereof, the damping device may be installed inside a refrigerator door or refrigerator housing, rather than the bottom surface of the refrigerator. Further, the damping device may be mounted inside the lower end portion of a front panel of the refrigerator door, resulting in an ease of an exchange and repair thereof.

Further, according to the present invention, the damping device may reduce the number of elements and the volume of a space required for the installation of a link device, resulting in enhancement in simplicity and easy assembly of the link device.

Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. 

1. A refrigerator, including a housing and a pair of doors that are coupled to the housing in a hingedly rotatable manner, the refrigerator comprising: sets of link devices to respectively transmit a rotating force of each of the doors relative to the housing; a damper, associated with each of the doors, coupled to the respective link devices, to absorb a shock to each of the doors and to allow each of the doors to be automatically closed.
 2. The refrigerator according to claim 1, wherein each damper includes: a substantially cylindrical casing; a cam member coupled to each of the link devices so as to convert the rotating motion of the associated one of the doors into linear motion; a piston, coupled to the cam member inside the casing, to move linearly; and a spring anchored to the casing and oil charged inside the casing to dampen the linear motion of the piston.
 3. The refrigerator according to claim 2, wherein the damper is mounted vertically inside the door.
 4. The refrigerator according to claim 2, wherein the cam member of the damper comprises a substantially hollow shaft having spiral grooves, wherein the piston is coupled to the cam member to linearly move along the spiral grooves, and the cam member converts the rotating motion of the door, transmitted through an associated one of the link devices, to the linear motion of the piston.
 5. The refrigerator according to claim 2, further comprising link connection portions to couple the cam members to the respective link devices, wherein each cam member is positioned inside each cylindrical casing so that the link connecting portion is provided at one end of each cylindrical casing and protrudes outwardly to allow the link device to be rotatably fitted therearound.
 6. The refrigerator according to claim 5, wherein the damping device further includes a sealing member, which is fixed around the piston to seal the oil charged around the piston inserted inside the casing.
 7. The refrigerator according to claim 4, wherein the cam member and the piston are coupled to each other by guide pins so that the piston is linearly movable within a range of the spiral grooves formed at the cam member.
 8. The refrigerator according to claim 7, wherein the guide pins are located close to a lower end of the cam member in a closed state of the door, and slide upward along the spiral grooves toward an upper end of the cam member by receiving an external force when the door is opened, so as to allow the oil to be compressed by a sealing member.
 9. The refrigerator according to claim 8, wherein the guide pins allow the door to be smoothly and/or automatically closed as they are returned toward the lower end of the cam member by making use of a repulsive force of the spring and/or the oil.
 10. A refrigerator comprising a housing, and a pair of doors coupled to the housing in a hingedly rotatable manner, the refrigerator further comprising: damping devices provided at the doors or the housing; and link devices to connect the housing and the respective doors and to transmit a rotating force of the doors to the damping devices.
 11. The refrigerator according to claim 10, wherein each of the link devices includes a first link member and a second link member.
 12. The refrigerator according to claim 11, wherein each of the first and second link members has rotatably connectable joint portions at both ends thereof.
 13. The refrigerator according to claim 11, wherein the first and second link members partially overlap each other while forming a small angle therebetween in a closed state of an associated one of the doors, whereas they are spaced apart from each other by a certain large angle when the door is opened.
 14. The refrigerator according to claim 12, wherein fasteners to rotatably connect the first and second link members to each other are coupled to the respective joint portions.
 15. The refrigerator according to claim 10, wherein each link device is adjacent to a central axis of rotation of an associated one of the doors.
 16. The refrigerator according to claim 10, wherein each link device includes a hinge member and a hinge shaft, wherein one end of the hinge member is fixed to the housing, and the other end of the hinge member is coupled to the associated one of the doors by the hinge shaft so as to secure rotation of the door.
 17. The refrigerator according to claim 2, wherein the damper is mounted vertically inside one of the doors.
 18. A damping device to dampen to absorb shock applied to a refrigerator door and to automatically close the refrigerator door, comprising: a hinge to rotably connect the door to the refrigerator so as to allow the door to rotate from a first position in which the door closes the refrigerator to a second position in which the refrigerator is open; a damper including a cylindrical casing, a cam to translate the rotational movement of the door to linear movement, a piston coupled to the cam to move linearly in accordance with the translated rotational movement, and a spring anchored to the casing to oppose the movement of the piston in one direction and aid the movement of the piston in the other direction; and a link system to connect the hinge with the damper so as to actuate the damper.
 19. The damping device according to claim 18, wherein the damper is coupled to the door via a support member having a cylindrical guide portion into which the piston is inserted and a circular center opening.
 20. The damping device according to claim 19, further comprising a link connecting portion to integrally protrude from the end of the cam, the link connecting portion having a cylindrical section to extend through the circular center opening of the support member and a rectangular section to cooperate with the link system.
 21. The damping device according to claim 19, wherein the link system comprises: a first link member having a rectangular hole to cooperate with the rectangular section of the link connecting portion at a first end thereof; and a second link member to be coupled to a second end of the first link member at a first end thereof and to be coupled to the hinge at a second end thereof.
 22. The damping device according to claim 19, wherein the second link member is longer than the first link member. 